A correlational study of cough sensitivity to citric acid and radiographic features of airway compromise
Thesis DisciplineSpeech and Language Sciences
Degree GrantorUniversity of Canterbury
Degree NameMaster of Science
Patients with an impaired reflexive cough response are at increased risk of pneumonia. This study examined the correlation between cough sensitivity to citric acid and radiographic features of airway compromise. Eighty patients referred for a radiographic assessment of swallowing at an acute hospital over an 8-month period participated in the study. Nebulised citric acid diluted in 0.9% sodium chloride was inhaled through a facemask at four concentrations to assess cough sensitivity. These data were then compared to Penetration Aspiration Scale scores based on radiographic swallowing studies. There was a statistically significant correlation between cough response/lack of response and the radiographic features of airway compromise; that is, patients who had a weak or absent response to inhalation of citric acid were also likely to aspirate silently during radiographic assessment. Sensitivity for identifying absent cough was found to be high at all 4 concentrations (0.750, 0.833, 0.941, 1.000), however specificity was consistently quite low (0.344, 0.456, 0.238, 0.078). The significant findings of this research suggest that clinicians adopting cough reflex testing into their clinical practice will have a reliable screen for silent aspiration at bedside. Clinicians will be able to identify patients who require instrumental assessment and are at high risk of pneumonia. This will likely, in turn, decrease length and cost of hospital admissions as well as decrease aspiration pneumonia related morbidities.